Electric Vehicle Progress

[10BaseT.]

I may be mistaken but isn't the throttle pedal a torque control while the engine is loaded ? Only when unloaded does the throttle pedal become a speed control - least on an IC engine .

I would have thought the drive reference would be torque not speed - the thing will try an tear itself to pieces otherwise .

 

[leitmotif]

So the same throttle position would result in a constant speed reqardless of whether going up hill or down hill? That isn't the way a gas powered car works, but you wouldn't need speed control because it would be built in.


The speed reference idea will work but one must ramp the speed reference up to avoid the wheelies.

Peter
Agree I will need to have a speed ramp to start out from stop without wheelie or tire spin (both good crowd pleasers on drag strip but city streets are not appropriate AND police in Seattle are real tough of racing or demonstration of speed ie smoking the tires)

With a constant throttle setting (constant volt / desired speed) input to VFD I would assume in theory speed should stay constant whether flat uphill or downhill. But in reality more throttle would be needed uphill due to increased torque and resultant decreased motor speed and the opposite for downhill. Just like with ICE.

My main issue with torque and attempt to control it or limit it is in starting to avoid wheel spin. In a car on slick icy road you feather the clutch and maybe use second gear to limit torque to avoid wheel spin. Once you get rolling most of the problem goes away as long as you are a little gentle on throttle.

I assume same would be true for VFD. Once up to speed say 5 mph or more I think the issue will go away and the throttle setting will control speed and torque just like you do in a car. Of course if at 5 mph you "floor the throttle" and send a 60 mph signal to the VFD it may get a little exciting.

LATER ON much later on
I want to test a theory of mine where on a drag strip
IF I can put maximum power to the pavement
AND not spin a tire (wasting energy and acceleration)
I should be able to get maximum acceleration, the shortest ET and max speed.

Dan.

 

[John Gaunt]

Look at Traction Control

Perhaps rather than worrying about Speed or Torque control it might be worth finding out about "Traction Control" as used in Formular 1 racing cars and a number of European high performance road cars.
The Formular 1 cars also use "Launch Control" just at the very start of the standing start race to prevent excessive wheel spin.
I think that in either case they somehow monitor the wheel rotation perhaps comparing the rear (driving) wheels with the front wheels.
Good luck with the project.

 

[OkiePC]

Opinion:
As a typical Okie "Git'rdone aholic"

I would say instead of theorizing and fantasizing, stick the motor in it and make it run and fix what don't werk right...

You will probably learn more from your first experiment about exactly what type of intellectual investment you want to indulge next.

Just my opinion...no disrespect intended...

Paul

'Cause the sooner you get done, the sooner I can build my 4WD 'lectric-hub Jeep!

Go Big Red!

 

[rsdoran]

When I first replied I thought this was a situation where someone was using something for a forklift etc. to do the conversion and did not read what was on the links provided.

Now that I have read where the components are coming from I wonder why the wheel is being reinvented? That company, in the link, provides conversions specific to Isuzu along with other things.

Since the company already has a track record of conversions, why the need to do this again, their information should be used to at least develop the basic parameters for the drive THEN investigate what can be done to possibly increase performance.

In this case you are talking about someing basically 80HP to replace an engine that was probably twice or more then that originally.

I also expect the drag strip test would be futile, the laws of physics still apply. In other words the electric may work but I doubt you can make it perform near as well as the engine it replaced.

As I mentioned though, I ain't the sharpest knife in this drawer.

 

[kamenges]

I THINK if you operate a drive in velocity mode but use only proportional gain in the velocity loop it will act pretty similar to an IC engine driven vehicle with just a single input. Torque will be proportional to speed error. You will need to put your foot deeper into the accelerator as the driving load increases to keep the same speed (i.e. going up hill). If you pull your foot back far enough the speed command will cross over the actual speed and you will begin to regen. The farther you pull back the more you will regen. Use some reasonable torque limits in the drive and it will act pretty similar to a sluggish IC vehicle.


Keith

 

[OkiePC]

The drive system numbers look idealized to replicate a pretty stout 4-banger. C'mon guys, those of you who read car craft should be able to notice the similarity in the charts...

The torque peak of ~203 foot pounds? With 103 continuous?

The horsepower spike right at the peak of the efficiency?

How does that compare with the Isuzu?

How much weight Gross Vehicle Weight change are you anticipating?

Darn thing just might break traction, but I think not because:

In speed mode, the programmed accel rate prevents wheel hop. You may have to change the accel rate dynamically so it will launch hard, but not try to break free at 60mph on a bumpy road...

Your foot feed is a speed reference, which should not cause spin during suspesion travel, wet surfaces. It, unlike a gas power drive, will still be trying to match the speed based on the controller feedback. If it accurately maintains speed, and suddenly loses torque requirement at the wheel, the wheel should not accelerate much if at all...now if both tires leave the ground, that is different...your open differential and closed speed loop should prove more drivable than the stock engine.

Where can I read the drive manual?

I want one!

Can I ask what a system like that will $et you back?

 

[bikerdude]

Okie,

You & anyone else can get a "kit" for $6,000 to $10,000. Everything except the batteries, battery mounts & labor to install.
http://www.electroauto.com/catalog/price-pts.shtml

Usual weight change is +600 lbs.

 

[leitmotif]

The drive system numbers look idealized to replicate a pretty stout 4-banger. C'mon guys, those of you who read car craft should be able to notice the similarity in the charts...

The torque peak of ~203 foot pounds? With 103 continuous?

The horsepower spike right at the peak of the efficiency?

How does that compare with the Isuzu?

How much weight Gross Vehicle Weight change are you anticipating?

Darn thing just might break traction, but I think not because:

In speed mode, the programmed accel rate prevents wheel hop. You may have to change the accel rate dynamically so it will launch hard, but not try to break free at 60mph on a bumpy road...

Your foot feed is a speed reference, which should not cause spin during suspesion travel, wet surfaces. It, unlike a gas power drive, will still be trying to match the speed based on the controller feedback. If it accurately maintains speed, and suddenly loses torque requirement at the wheel, the wheel should not accelerate much if at all...now if both tires leave the ground, that is different...your open differential and closed speed loop should prove more drivable than the stock engine.

Where can I read the drive manual?

I want one!

Can I ask what a system like that will $et you back?

REPLIES

Any weight change hopefully will be lighter. In any case I will not go over GVW nor will I change front axle to rear axle weight ratio. I may have to sacrifice some payload capacity but if so then,,,

It does not seem right to compare ICE to electric UNLESS I have matching torque values and measurements. That will never happen unless I have a dyno guy hook both units and test under identical protocols. There are several spreadsheets and I have read several books on how to do this. Basicallly
torque = sum(rolling torque, plus windage torque plus toque imposed by grade). The calcs for my Izuzu come out to needing about 15 HP for rolling torque, and about another 22 for windage.

Website for factory is on my initial post. you can get a pretty fair overview there. Write sales attn Beth Silverman for manuals.

Have not looked into the price yet for two reasons
1. Still plugging pennies into piggy
2. Really want to deal with factory not their authorized vendor. Am trying to convince them to sell to me direct.
3. If I have to buy thru a vendor I will deal with a vendor here in Seattle that way I keep money in my own community.
Just a guess at this stage about 8 to 10K for entire kit.

Dan Bentler

 

[leitmotif]

Okie,

I completely agree with get r done but still try to keep ignorant mistakes to a minimum. All the reading, calculations, design work go out the window when the first wrench gets picked up. That is when my real education starts. The school of hard knocks has always been expensive for me but I remember the lessons well/

Now then among other pipe dreams I have one where 4 WD will be four independent motors (hub mounted ideally). Ideally will use 4 VFDs slaved such that I can turn off any one and cripple home on two or three motors. Let me get good at this and I will build it for you.

Dan

 

[leitmotif]

Perhaps rather than worrying about Speed or Torque control it might be worth finding out about "Traction Control" as used in Formular 1 racing cars and a number of European high performance road cars.
The Formular 1 cars also use "Launch Control" just at the very start of the standing start race to prevent excessive wheel spin.
I think that in either case they somehow monitor the wheel rotation perhaps comparing the rear (driving) wheels with the front wheels.
Good luck with the project.

John
I guess Traction Control is another good term for what I am trying to do - which is transfer as much power as possible from the motor via the drivetrain and tires to the pavement with minimal losses such as tire spin.

Where can I learn more about Traction Control and their Launch Control??

Dan

 

[Sleepy Wombat]

I thought that i would just add this little link FYI...

drag racing with an electric motor bike...

make sure you also check out the clips on you tube for it as well.. amazing...

http://autospeed.drive.com.au/A_108827/cms/article.html

 

[10BaseT.]

John
I guess Traction Control is another good term for what I am trying to do - which is transfer as much power as possible from the motor via the drivetrain and tires to the pavement with minimal losses such as tire spin.

Where can I learn more about Traction Control and their Launch Control??

Dan

Read any forum that deals with cars that have ESP etc - Merc forums if you like - they brake the wheel that loses traction until both driven wheels lose traction then back off the throttle (read TORQUE) control .
All this talk of wheelies and tyre smoke - of course your axle will put up with this ?

You will of course be installing a steering angle sensor so that your traction control knows you are going around a corner and doesn't put you into a tree trying to straighten you up - what about reg braking - going to all this trouble not to recover kinetic energy back to the power source seems a bit of a shame .

Why not take a look at how Toyota has dealt with the Prius ?

 

[leitmotif]

Read any forum that deals with cars that have ESP etc - Merc forums if you like - they brake the wheel that loses traction until both driven wheels lose traction then back off the throttle (read TORQUE) control .
All this talk of wheelies and tyre smoke - of course your axle will put up with this ?

You will of course be installing a steering angle sensor so that your traction control knows you are going around a corner and doesn't put you into a tree trying to straighten you up - what about reg braking - going to all this trouble not to recover kinetic energy back to the power source seems a bit of a shame .

Why not take a look at how Toyota has dealt with the Prius ?

REPLIES (in order)
Whole idea is to transmit max power to the ground with no loss ie wheel spin. Braking would be a loss. I would be controlling the amount of power (torque) input to the system instead of controlling at the output by braking.

Steering angle sensor - little complicated at this stage. Again if I control at the motor and use a differential I should get reasonable best efficiency.

Toyota Prius hmmm now there is a thought use an existing design. How novel.

Thanks
Dan

 

[DickDV]

Dan, the more I think about this, the more I am convinced that the equivalent of an ICE throttle is an analog torque input to the drive. Proof of this is to hold your foot stationary on the throttle and watch what happens to speed on a hilly road.

If simplicity and similar drivability with ICE is desireable, I would forego the complex electronics and simply use what gas engines use now- the driver's brain controlling the pedal to regulate the torque. Of course, you could set max torque limits.

As kamenges mentions, if you did use speed regulation, it would have to be very very soft. Otherwise, every movement of your foot would cause a full-torque speed correction to match and the result would resemble a bucking bronco. Also, only slight lifting of the foot would cause full regen braking---kind of like that bucking bronco running into a wall!

An ICE does produce a little engine braking when coasting and that could be done again as kamenges mentions. However, it seems to me that the throttle braking would only be slight, maybe 10%. More than that would have to come from the brake pedal. Exactly how to implement such operation would take a little study especially when mechanical braking is blended in at heavy brake pedal pressure or slow speeds.

Hmmmm! Cause for thought!